Traditionally, syringes are filled manually using a technique that requires the use of two hands, a syringe with a needle, and a vial. The process begins by drawing air into the body of the syringe, by pulling the plunger away from the needle end of the syringe until the volume of air in the body equals the volume of medication to be loaded into the syringe. The exposed needle is carefully aligned with a septum on the top of the vial and then inserted through the septum. The vial is turned upside down so that the medication covers the top of the vial and the depth of the needle is adjusted in the vial so that the needle tip is surrounded by the medication. Next, air is forced from the body of the syringe into the inverted vial, by pushing the plunger toward the needle end of the syringe until it is stopped at the end of the body. The user continues to hold the vial and the syringe in one hand, while using the other hand to pull back the plunger to draw out the desired volume of medication into the body of the syringe. Finally, the needle is pulled out of the vial and exposed. This process is generally conducted many times a day by care-givers, such as doctors and nurses, in care facilities, such as hospitals, nursing homes, or the like. It is also often carried out by patients at home that administer their own medication injections or use refillable infusion pumps.
One drawback to this method of filling a syringe is the user's exposure to an unprotected needle tip. Care-givers and patients can be pricked or stabbed by needles during the filling process or when disposing of the syringe needle. Generally, the exposure occurs twice during the filling process. First, when the protective needle cap is removed before inserting the needle into the vial; and second, when removing the needle from the vial. Typically the vial is held by hand while the needle is pushed through the septum. Thus, if the needle is misdirected to either side of the septum, the user could inadvertently drive the needle tip into the hand holding the vial. The potential of stabbing oneself with the needle increases when patients are in a weakened state or are shaky when they need to insert the needle through the septum. Second, unintentional needle pricks can also occur when pulling the needle from the vial, at which point the consequences of the user stabbing oneself may be greater, since the syringe contents may not be safe for the care-giver.
An additional drawback to filling a syringe using the conventional method is the difficulty of keeping the needle in the vial, while simultaneously holding both the vial and the syringe and then pulling the plunger back to draw out the medication. Also, as the amount of medication in the vial decreases, it may be difficult to keep the needle tip at the appropriate depth within the vial during filling so that the tip of the needle is always completely surrounded by the medication to avoid drawing air back into the syringe.
To overcome some of these drawbacks, stabilizing devices, such as the EasyFill device from Disetronic of Sweden, have been used to support the syringe and vial. For instance, a syringe with a filling needle is slid sideways into the EasyFill device and held in place with semicircular tabs. After the needle is inserted into a septum of a vial, additional semicircular tabs on the EasyFill device slide over and around the outside of the top of the vial. This makes it easier to hold the syringe, needle, and vial, while filling the syringe with medication from the vial. However, there are still drawbacks to using the EasyFill device. For example, once the protective cap is removed from the filling needle in preparation for insertion into the vial, the needle tip is exposed beyond the end of the EasyFill device and potentially could stab the user. In addition, the needle must still be carefully aligned with the septum in the top of the vial before inserting the filling needle. Also, when the EasyFill device is fully engaged with the vial, the tip of the filling needle is often inserted too deeply into the vial so that some of the medication can not be drawn out from the vial, resulting in wasted medication. Finally, once the filling needle is removed from the vial, the needle tip is exposed a second time so that the user can be inadvertently pricked or stabbed by the filling needle.